See: https://learn.microsoft.com/en-us/dotnet/api/system.io.compression.deflatestream?view=net-7.0

Deflate(bytes:Blob; inflate:Boolean):Blob  (set Eco.ExternalLateBound=true)

Example for compressing:

let compressedbase64=SysSingleton.oclsingleton.Deflate(xml.Replace('\r\n', ' ').Replace('\n', ' ').StringToBase64.Base64ToBlob,false).BlobToBase64 in
(
  SysSingleton.oclsingleton.UrlEncode(compressedbase64,false)
)

Example for decompressing:

vAnswer:=SysSingleton.oclsingleton.Deflate(vCert.RSADecrypt(  vAnswer.Base64ToBlob),true).blobtobase64

See also: SysSingleton.UrlEncode